Search found 17 matches

by abb.omidi
6 days ago
Forum: Modeling
Topic: Connecting GAMS 28.1.0 to neos server
Replies: 1
Views: 50

Connecting GAMS 28.1.0 to neos server

Dear support team, I'm trying to run the GAMS model using neos-server. I wrote the following code in the GAMS studio: Option mip=kestrel; sequence.optfile=1; $onecho > kestrel.opt kestrel_solver cplex neos_server www.neos-server.org:3333 $offecho But it doesn't work. I was wondering if, how can I co...
by abb.omidi
1 month ago
Forum: Modeling
Topic: Modeling the chance constraints
Replies: 0
Views: 64

Modeling the chance constraints

Hello support team, I have worked on the MIP model that contains the chance constraints. The constraint is: probability_cons.. prob[sum(j, a(j)*x(j)) =l= b] =g= beta; Where a(j) and b are given parameters and beta is the probability. I was wondering if, you say that, is there any efficient way to wr...
by abb.omidi
3 months ago
Forum: API
Topic: Read a MPS/LP file in Java
Replies: 2
Views: 250

Read a MPS/LP file in Java

Hello support team,

Would you please, say that is there any way (or any example) to read an "MPS/LP" file in the GAMS Java API and get output in the specific format? If so, could you advise me, please?

Regards
Omidi. A
by abb.omidi
3 months ago
Forum: Modeling
Topic: Using SOS type_1 constraint
Replies: 2
Views: 181

Re: Using SOS type_1 constraint

Dear Fred, Thanks for your useful comment. As per your advice, I try to use a medium scale problem using both binary and SOS1 variables. The results and solving time are the same. I think using of SOS1 does not improve solving time (in my problem). Unfortunately, I can not understand why GUROBI (Jav...
by abb.omidi
3 months ago
Forum: Modeling
Topic: Using SOS type_1 constraint
Replies: 2
Views: 181

Using SOS type_1 constraint

Dear support team, I was trying to solve a scheduling model using GAMS/Gurobi. The snippet code is: Binary variable x(i,k); Equations c1,c2; c1(k).. sum(i, x(i,k)) =e= 1; c2(i).. sum(k, x(i,k)) =e= 1; Using the binary variables, the model has solved optimally. I have used SOS type_1 variables instea...
by abb.omidi
4 months ago
Forum: Modeling
Topic: Lazy constraints
Replies: 4
Views: 315

Re: Lazy constraints

Dear Fred,

Thanks so much for your help.
I can do it and it works fine.

Regards
Omidi. A
by abb.omidi
4 months ago
Forum: Modeling
Topic: Lazy constraints
Replies: 4
Views: 315

Re: Lazy constraints

Dear Fred, Thanks for your replay. As per your comment, I try it and it works fine for cube problem while I try to run it on the "ROTDK" in the GAMS lib, it seems that it does not work properly. (it's solved optimally but did not apply any lazy constraint). AFAIK, to apply lazy in the GUROBI or CPLE...
by abb.omidi
4 months ago
Forum: Modeling
Topic: Lazy constraints
Replies: 4
Views: 315

Lazy constraints

Hello everybody,

Is there any way to use (or call) lazy constraint in GAMS modelling? If so, could you tell me how can I run it?

Thanks in advance
Omidi. A
by abb.omidi
11 months ago
Forum: Modeling
Topic: flexible job shop scheduling
Replies: 1
Views: 445

Re: flexible job shop scheduling

hello According to the model, you can use from a table (or parameter) to define model data. For example, you may have a process time parameter (time of operation of jobs) or a route parameter (binary parameter: 1 if the operation of j pressed before operation of i in machine k, otherwise 0) that dep...
by abb.omidi
11 months ago
Forum: Modeling
Topic: Logical constraint
Replies: 0
Views: 639

Logical constraint

Hello everybody I have a question about coding logical constraint in the GAMS IDE. Please, let me describe optimization model: { set i /1*2/; parameter cost(i); integer variable nb(i); .... of.. obj =e= sum(i,cost(i)*nb(i))+(x-1)*500; con1.. sum(i,nb(i)*ns(i)) =g= N; } There is a logical constraint ...